With vintage, 70mm shell width is "normally" Italian. 68mm is "normally" everything else. There are always exceptions to the rule with bottom bracket shells, probably most notably with Swiss and Brits, like, some Raleighs using 73mm shell width on some things, Swiss being unable to make up their mind on whether to thread ISO or like the French.

I stand by my thoughts. Both names I mentioned (Bottecchia, Bianchi) are Italian. But there were so many small shops producing one-off (contracted) builds we could look forever.

"Jebiga" may apply here.